Ephorus of Cyme (ˈɛfərəs; Ἔφορος ὁ Κυμαῖος, Ephoros ho Kymaios; 400 - 330 BC) was an ancient Greek historian known for his universal history. Information on his biography is limited. He was born in Cyme, Aeolia, and together with the historian Theopompus was a pupil of Isocrates in rhetoric. He does not seem to have made much progress as a speaker, and at the suggestion of Isocrates himself he took up literary composition and the study of history. According to Plutarch, Ephorus declined Alexander the Great's offer to join him on his Persian campaign as the official historiographer. His son Demophilus followed in his footsteps as a historian. Ephorus' magnum opus was a set of 29 books recounting a universal history. The whole work, edited by his son Demophilus—who added a 30th book—contained a summary description of the Sacred Wars, along with other narratives from the days of the Heraclids up until the taking of Perinthus in 340 BC by Philip of Macedon, covering a time span of more than seven hundred years. According to Polybius, Ephorus was the first historian to ever author a universal history. For each of the 29 separate books, Ephorus wrote a prooimion. The work was probably simply named Historiai, and followed a thematic, rather than a strictly chronological order in its narrative. These writings are generally believed to be the main or sole source for Diodorus Siculus' account of the history of Greece between 480 and 340 BC, which is one of only two continuous narratives of this period that survive. It is clear that Ephorus made critical use of the best authorities. His history was highly praised and read in antiquity, and later ancient historians freely drew upon his work. Large parts of the history of Diodorus Siculus may have originated in Ephorus's history. Strabo attached much importance to Euphorus's geographical investigations, and praised him for being the first to separate the historical from the simply geographical element. In his Geographica, Strabo quoted Ephorus at length.